In a pptx file with a slide master that has multiple slide layouts, the footer would loose properties when saved in LO and opened in MSO. This is due to the master de-duplicating logic that in trying to emulate pptx's natural way of dealing with master and layout slide it treats multiple Impress masters as equivalent. This is needed for most export functions, but when exporting an element from an Impress slide that references an Impress master (like a footer), we need to differentiate exactly which one of the equivalent masters it comes from to make the indices match. Change-Id: I815c3db54256d934b69108c7268f6d7642c33cbb Reviewed-on: https://gerrit.libreoffice.org/c/core/+/194190 Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoffice@gmail.com> (cherry picked from commit 0f21756af8e74b0dd3f25fe4234feb067430838b) Reviewed-on: https://gerrit.libreoffice.org/c/core/+/195225 Tested-by: Jenkins Reviewed-by: Jaume Pujantell <jaume.pujantell@collabora.com>